Bottom take-off for air conveyers



y A118l8r1950; A H. A. BRowNE Erm. 2,517,837

o'r'rou TAKE-on von un commas Filed April 5, 1949 2 Sheets-Shoot 1 1N V EN TOR.s

By Hara/a /70 Uma/7 u- 8 1950 H. A. aRowNEjTAL 2,517,837

Bo'r'ron frm-OFF Fon AIR coNvEYBRS Filed April l5, 1949 2 shuts-sunt 2 IN V EN TUR? F IE7. l Hefef/ A. rown@ a Haro/0 D. //fmah A TroRNc Ys UNH-SDL STAT I Patented Aug. i8, 21950 j ,2.51am BOTTOM Tann-oFF Fon Ala coNvEYEns Herbert A. 'Browne and nanna n. Hillman,

Alpena, Mich.,-assignors to. Huron Portland' Cement Company, Detroit, Mich., a corporatio of Michigan Application A p'ru 5, 1949, serial No. sassz (ci. 3oz-29) 11 Claims.

" This invention relates to 'a material take-ol! for an air conveyor. I

Air conveyorsarev now in use for transportingV fine pulverulent dry material. Such an air conveyor comprises an inclined porous medium which supports a stream of pulverulent material which' is aerated, so that' it has somewhat the characteristics ofa iiuid,` by low pressure' air passing'through the porous medium and the aerated material `flows downv the inclined porous support duetoigravity. ySuch an air conveyor is shown in theefcopending' application oli-Henry Ripley Schemn'i.' Serial No. 602,094, tiled June28. 1945,"'now abandoned. Su'ch air conveyors are utilized to convey numerous iinely divided materials such as cement, sodaash, bentonite, lime, andthe raw materials from which Portland cement is compounded. yIt is often vhighly desirable in the use'of an air conveyor' to divert all or part of the stream of pulverulentmaterial from the conveyor. .f1 e

It is an object of this invention to produce a take-oil for anair conveyor which is of simple structure, efiicient in operation, -simple to install in the conveyor." line, easy to operate, and substantially trouble-free' in v operation. n

Fig. lis a side elevation showing our'material "take-oil assembled in'an air conveyor.

7 butshowing the -gatefully closed.

Referring more particularlyv to the drawings there is shown atypical air conveyor inthe form of metall channels Ia'nd 2, porous medium 3 ex tending-across channel 2 throughout its length and resting u'p'onthe outwardly turned flanges 4 of the' side walls 5 'of 'channel 2. The upper channel I yis inverted and? positioned 'upon the porous .medium 3 and bolted to'tli'ef'lower channel 2 by 'means of bolts which? -pa'ss'through flanges 1 vof fup'per channel I, a'ngsj( andthe 'intervening edges of the porous" medium 3. The 'porous medium3 Vcooperates:'with upper channel I totorm a material duct 8l andwith lower channel' 2 to forx'n an air duct il. Lowjpressureaigissupplied fto duct "9 'from ajblowerl run by-fan electric a static'pressure in the neighborhood of two, tu sixteen inches water sauge but in .some instances, 'depending upon the head of material in the conveyor; this pressure will run as high as two andv one-half pounds per square inch. Powdered material is'supplied to duct 8 from hopperl2. i' i" Porous medium 3 can be porous filter stone but .preferably takes theiorm of any -low permeability woven fabric material 'and can be woven, e. g., from cotton or othercellulose iibers or from spun glass bers. Finely woven, heavy canvas belting is especially advantageousr as a porous medium. Such canvas belting is usually a woven multiple ply belting and is vusually designated commercially by'the number of plies it contains. Single ply woven canvas belting can be used but multiple ply woven canvas belting is preferred, for. ex'- ample, any number ofplies from two to eight plies. r v The permeability of the porous fabric will be such that at the low pressures above indicated it will pass from two to twelve cubic feet per minute of air through each square foot ofxarea. We

have found lthe lcanvas belting to be exception- 'ally etllcient where it passes about two tof-four cbic feet per minute of air` per square footof canvas at a' static pressure in the neighborhood o ftwo to eight inches water gauge. lThe air ilowing through the porous medium 3 aeratesthe pulverulent umaterial which mayltake the form, for example, of d ry powdered cement, mortar, cereal, ilour or powdered plastic.' 1

The porous medium lis planar vin form and is inclined preferably at an angle slightly greater than the angle of repose of theaerated material. The ilow'of material is indicated by the-arrow and the optimum angle of inclination to the horizontal for the conveyor is about five degrees. I

Our material take-ofi comprises a housing I 3 having side walls'IL'top wall -IS'and end-walls I6 having opposed openings I1 therein of the same area `as the cross-sectionalarea'otmaterialv duct 8.'- Housing I3 is assembled inthe air conveyor so that openings `I1 are aligned with Athe ends of material ducts I and so that the end `walls Il close the ends of air ducts 9. The lower end of housing I3 is'open as at IB.

A bypass conduit I9 connects into air ductl 9 on opposite sides of housing' I2y as (atzliand 2l so that'glowfpressure 'fair is vcontinuouslybypassed vfrom theportion of air "ducty s 'to the rient o of housing n tothe `portails or air duct) s tothe lei't of housing I3.l Thus,;bypass' I9`pe'r- -m-its one blower I0 to furnish-air tothe air-'conveyor throughout its length on opposite sides of the take-ou.

An aerated gate is provided for bridging the gap or opening 53 between the ends 5I, 52 of porous medium 3. This gate should be removable from said gap 50 so as to connect gap 50 with duct 8 to the rightof housing I3. To this end an aerated gate 25 in the form of a sheet metal box 25 having an opening 21 in the top thereof is mounted in housing I3. Gate 25 has the same contour as the cross-sectional contour of housing I3 and thus has a snug fit in housing I3. Gate 25 is removable from opening 50 preferably by lifting the same vertically in housing I3.

Opening 21 is closed by a porous medium 28 preferably of the same material as porous medium 3. Preferably porous medium 28 is a multiple ply canvas fabric and extends over opening 21 and is clamped to box 25 around the periphery of opening 21 by clamping ring 29.

Air is supplied to gate 25 by pipes 30 and 3I which are reciprocably mounted in cylindrical guides 32 and 33 xed to the top I5 of housing I3. Gate 25 is dimensioned so that it will span the space between openings I1 in housing I3. '.I'he bottom of gate 25 is tapered and in lowered position is arranged to seal against rectangular flexible seat 34 fixed in housing I3.

For moving the gate 25 upwardly and downwardly there is Vprovided an air cylinder 35 mounted centrally on top I5 of housing I3. Piston 35 is reciprocably mounted in cylinder 35 and carries a piston rod 31 which supports cross pipe V 35 w-hich is connected to, and communicates with,

the upper ends of pipes 30 and 3I. A flexible hose 39 communicates with air duct 9 as at 40 and with pipe 38 as at 4I to supply air through pipe lines 30 and 3| to gate 25 from which it passes upwardly through fabric 28. Compressed air for raising piston 35 is supplied to cylinder 35 through air line 43 controlled by valve 44 through which air can be admitted to, and exhausted from, cylinder 35.

A damper 45 is pivoted on shaft 45 in material duct 3 and is connected by meansof crank arm 41 and link 48 with bar 43 which is clamped or otherwise fixed to pipe 30.

In lowered operative position, Fig. 8. gate 25 seals against iiexible seat 34 and porous top wall 28 is flush with fabric 3 in conveyor I, 2. Gate 25 forms an aerated iloor between openings I1 in housing I3 so that gate 25 cooperates with housing I3 to form connecting air and material ducts between the air and material ducts (9, 8) on opposite sides of housing I3. Since air is supplied continuously through lines 39, 38, 3l and 3l to gate 25, this air passes through porous fabric 28 and aerates the material thereover. Thus, with the gate in lowered position, material ilow continues right through air conveyor and at this time, of course, damper 45 will be open, dotted line showing, Fig. 6.

If it is desired to take oif the material from the air conveyor, then compressed air is admitted to cylinder 35 which acts through piston 3B and rod 31 and pipes 3I to raise gate 25 to the full line position shown in Fig. 7, thus removing the bridge between the material ducts 8 which connect into openings I1 on opposite sides of the housing I3.

With gate 25 elevated, the material flows through air duct 8 until it reaches the right hand opening I1 whereupon the material falls downwardly in housing I3 and through opening I8 into discharge duct 5I. When gate 25 is elevated.

Y 4 damper 45 is closed so that if any material should Y slop over through left hand opening I1 this material will be stopped by the fully closed damper 45. It is understood that bypass I9 at all times ksupplies air from fan III from the air duct 3 on the right hand side of housing I3 to the air duct 9 on the left hand side.

The top of gate 25 should preferably be made porous throughout as great an area as possible. The ideal condition would be to have porous top 28 extend from one opening I1 to the other opening I1 in housing I3 so that the aeration of the material flowing through the housing and over the gate will notbe interrupted. As a practical matter, porous web 28 covers a substantial portion of the area in housing I3 between opening I1 and is suiilcient to aerate the material and continue its flow through the material take-off when the gate is lowered.

Air pipe lines 30 and 3| raise and lower with gate 25. As pipe 3U raises it acts through link 48 and crank 45 to close damper 45 and as pipe 30 lowers with gate 25, link 48 and crank 46 operate to open damper 45.

We claim: I

1. A material take-'off for an air conveyor adapted to convey aerated pulverulent material comprising a housing having an inlet opening for aerated material and an outlet opening for aerated material spaced from said inlet opening,

, a movable gate for bridging the space between ing through said porous top wall and ows from the' inlet over the gate and through said outlet.

2. The material take-0i! claimed in claim 1 wherein the inlet and outlet openings are located in the side walls of said housing and the gate in bridging position has the porous top wall substantially ilush with the lower edges of said inlet and outlet openings.

3. The material take-olf claimed in claim 2 wherein the housing has an opening in the bottom thereof and means are provided for elevating the movable gate above the lower edge of said inlet opening whereby the material ows from the inlet opening downwardly through the housing and outwardly through the bottom opening.

4. A material take-off for an air conveyor adapted to convey aerated pulverulent material comprising a housing having an inlet opening through which the aerated material flows into the housing and an outlet opening spaced from the inlet opening through which the aerated material iiows out of the housing, a movable gate for bridging the space between said openings, said gate comprising a hollow body having a porous top wall, means for supplying gas under pressure into the hollow body whereby when the gate is in bridging position between said inlet and outlet openings the pulverulent material is aerated by gas passing through said porous top wall and flows from the inlet over the porous top wall and out of said outlet.

5. The material take-olf claimed in claim 4 wherein the gate is reciprocable in said housing into and out of bridging position and wherein the inlet and outlet openings are positioned in the side walls of said housing.

6. The material take-off claimed in claim 5 wherein the gate in bridging position has its porous top wall substantially flush with the lower edges of said inlet and outlet openings, and means for elevating the gate whereby the porous top wall will be raised above the lower edges of said inlet and outlet openings and the ilow of material through the housing interrupted.

7. A material take-off for an air conveyor adapted to convey aerated pulverulent material comprising a housing having an inlet opening for aerated material and an outlet opening for aerated material spaced from said inlet opening, a movable gate for bridging the space between said openings, said gate having a top wall of woven fabric material, and means for supplying gas under pressure to said gate whereby when the gate is in bridging position between said inlet and outlet openings the pulverulent material is aerated by gas passing through said fabric top wall and iiows from the inlet over the gate and through said outlet.

8. The material take-01T claimed in claim 7 wherein the woven fabric is a multiple ply canvas belting material.

9. In combination an air conveyor adaptedV to convey aerated pulverulent material comprising a housing having inlet and outlet openings therein, an inclined porous support leading to said inlet opening, an inclined porous support leading from said outlet opening, a plenum chamber beneath each of said porous supports containing gas under pressure which nows upwardly through said porous supports to aerate the pulverulent material iiowing downwardly thereon, a gate in said housing having a porous support for bridging the gap between the inlet and outlet openings, said gate including a plenum chamber beneath said porous support containing gas under pressure which flows upwardly through said porous support to aerate the pulverulent material thereon, said gate in one position having its porous support aligned with the porous supports of said air conveyor whereby the aerated material flows through the inlet across the gate and out of the outlet, said gate in another position having its porous support offset from the porous supports in said air conveyor whereby flow of aerated material from the inlet to the outlet opening is interrupted.

10. The combination claimed in claim 9 wherein the housing has a bottom opening through which the material flows from said inlet' opening when the gate is positioned with its porous support offset from the porous supports of said air conveyor.

11. The combination claimed in claim 10 including an air bypass conduit between the plenum chambers on opposite sides of said housing.

HERBERT A. BROWNE. HAROLD D. HILLMAN.

No references cited. 

